There are a few reasons why your tooth might hurt when you eat. It could be that you have a cavity or two, which means there is bacteria present in your mouth that is causing the pain. It could also be that you have an infection in your tooth, which can be extremely painful. If you are experiencing pain in your tooth whenever you eat, it is important to see a dentist as soon as possible to get it checked out.
Possible reasons for toothache
1. You could have a cavity or two.
2. You could have an infection in your tooth.
3. Your gums could be inflamed.
4. You might have grinding your teeth at night
5. Aggressive brushing habits
6. Eating hard foods
7. Use of dental appliances such as braces
8. A loose filling
9. Sinus infections
10. Jaw joint disorders